1. Field of the Invention
The present invention relates generally to integrated circuit (IC) packages, and more specifically to containing electromagnetic interference (EMI) generated by integrated circuits.
2. Background Information
Many electronic devices such as integrated circuits generate undesirable amounts of EMI. Typically, the “noise” generated by the integrated circuit originates from the die, and its connections to the pins through the package, and is coupled to the heatspreader or lid covering the die and then to the heatsink, which acts as an antenna that further radiates the EMI. As the EMI is coupled to neighboring components and integrated circuits, it interferes with their individual performance which may, in turn, affect the overall performance of a system. Because of the negative effects of EMI and because the level of acceptable radiated EMI is subject to strict regulatory limits, it is desirable to contain or suppress the EMI generated by an integrated circuit.
Some solutions involve grounding the heatsink and building a Faraday cage around the EMI producing chip (e.g., a CPU). This solution typically involves the use of a grounded gasket that surrounds the chip and makes contact with the heatsink. The effectiveness of this solution is dependent on having good contact between the gasket and the heatsink and between the heatsink and the chip lid. In addition, because of the gasket contacts with ground on the top layer of the PCB, the routing of the pin escapes on the top layer may be very difficult or even impossible. In such a situation, the PCB may need additional layers which increases the cost of the PCB. Furthermore, the gasket itself represents an additional cost and potential point of failure, as it is a separate part that must be added to the PCB. Gaskets may take up space on the printed circuit board in the area surrounding the chip that might otherwise be used for electronic components.
It would be beneficial to have an EMI containment system that does not require elements external to the chip package and which allows for routing of pin escapes on the top layer of a PCB.